i 9 4 HUXLEY AND NATURAL SELECTION 



and its causes. In October of the following year, when a 

 few months under thirty, he read Malthus On Population, 

 and the idea of Natural Selection at once dawned on his 

 mind. In June, 1842, he wrote a brief account of the 

 theory in thirty-five pages, expanded two years later into 

 an essay of 231 pages, folio ; but he could not bring him- 

 self to publish until, on June 18, 1858, almost exactly 

 twenty years after the conception first came to him, he 

 received a manuscript essay written by Alfred Russel 

 Wallace at Ternate, in the Moluccas, On the Tendency of 

 Varieties to depart indefinitely from the Original Type. In 

 the accompanying letter Wallace asked him if he thought 

 well of the essay to send it to Sir Charles Lyell. In the 

 paper which had reached him from the other side of the 

 world Darwin was astounded to find a clear, concise 

 statement of his own theory of Natural Selection. He 

 sent it on to Lyell that very day and shortly afterwards 

 asked him to forward it to Sir Joseph Hooker. Thus 

 appealed to, Lyell and Hooker requested Darwin to give 

 them an abstract of his own work, and presented this, 

 together with Wallace's paper, as a joint communication 

 to the Linnean Society. They explained the circum- 

 stances of the case in an introductory note to the Darwin- 

 Wallace memoir, which was read at the meeting held on 

 July i, iSsS. 1 



That, of two naturalists on opposite sides of the globe, 

 one should seek the other for advice upon the theory at 

 which they had independently arrived, is a sufficiently 

 remarkable fact in the history of discovery ; but now that 

 we know the circumstances under which Wallace wrote 

 his essay, the coincidence is far more striking. He also 

 was convinced of Evolution before he thought of a motive 

 cause, and had in 1855 defended it in a powerful paper, 

 written in Borneo, On the Law which has regulated the 

 Introduction of New Species. In February, 1858, lying 

 ill of intermittent fever in Ternate, he, too, began to think 

 of Malthus On Population, which he had read some 



1 In addition to the specially prepared abstract, Darwin's section of 

 the joint memoir includes a copy of a letter he had written Sept. 5, 1857, 

 explaining his theory to Asa Gray, the great American botanist. 



